Have you read the ICNIRP guidelines?  These can be downloaded from the ICNIRP web site (link below).

A 2013 paper by Karl Schulmeister discusses recent changes to IEC60825-1 and ANSI Z136.1, standards and may be of use.

http://www.icnirp.org/cms/upload/publications/ICNIRPLaser180gdl_2013.pdf

http://laser-led-lampen-sicherheit.seibersdorf-laboratories.at/fileadmin/uploads/intranet/dateien/2013_ILSC_The_upcoming_new_editions_IEC60825-1_ANSI_Z136-1_Schulmeister.pdf

https://www.researchgate.net/post/Laser_Saftey_Classification_How_can_I_find_out_classes_under_IEC_60825-1

Thank you  Alan . Yes I have seen these papers . actually I was looking for  ANSI Z136.3 – Safe Use of Lasers in Health Care which is more specific. But I am not getting much information related to the same. 

There is more UV-related information in the ICNIRP UV exposure guidelines.

I can't help with specific health care related issues.  Do you have a Laser Safety Officer who can advise on your local guidelines and procedures?

ICNIRP 2013 (table 5). exposure limit at 281 nm is 30 J m-2.  The older UV guidelines (2004) spectrally adjusted limit is 34 J m-2.  There is a single pulse limit of 49 J m-2 for 6 ns pulses in ICNIRP 2013, which is less stringent in this case.

For exposure times between 0.35 s and 10 s an aperture size between 1 mm and 3.5 mm is specified (ICNIRP 2013 table 5).  If the intensity varies within your 10 mm spot you must calculate the worst case intensity averaged over the specified aperture.  A 1 mm aperture will be conservative, and should be used if your application suppresses subject movements during the exposure.

For example, if intensity in the centre of your spot is 2x mean intensity over a 5 mm radius circle (area 78.5 mm2), then the peak energy density per pulse is (2 x 200) / 78 = 5.1 J m-2.

With these assumptions, exposures should be limited to a few pulses at most.  For a 0.5 second exposure, the aperture diameter for intensity calculations is 1.5 t0.375 mm, so 1 mm would be conservative.

http://www.icnirp.org/cms/upload/publications/ICNIRPUV2004.pdf

http://www.aslms.org/news/documents/RevisionofANSIStd2.2012.pdf